Automatic anti-glare rearview mirror system

ABSTRACT

An automatic anti-glare rearview mirror system includes an anti-glare rearview mirror, a rearview mirror drive circuit, a backward light level sensing device, an ambient light level sensing device, a backward and ambient light level comparison circuit, and an enforced DAY level control device or an enforced DAY level setting device for controlling an anti-glare mode of the mirror according to the ambient light level. The enforced DAY level control device varies the ambient light level to operated an enforced DAY generation circuit by informations from a clock circuit other than a photo-sensor, any time operable switches and variable controller or a light switch ON of an automobile of itself. The high accurate automatic anti-glare mode which has not been taught by conventional prior arts is achieved to be adequate for an actual using condition so as to overcome the disadvantage that the rearview mirror becomes the anti-glare mode at the gray place such as a tree shade in a day time and the backward being not bright, to the contrary, to enable the rearview mirror to become the anti-glare mode adequately at a comparative bright place such as a shopping arcade in a night time.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an automatic anti-glare to ananti-glare rearview mirror system capable of varying an ambient lightlevel to operate an enforced DAY generation circuit by an informationother than an photo-sensor.

2. description of the Relevant Art

It is known that the rearview mirror of the automobile is of theautomobile so that the driver can obtain the backward sight during theautomobile running. During night driving, due to a bright reflection ofthe rearview mirror caused by the backward automobile head light and bya street light, it is impossible to prevent the driver's eyes from aglare light under the same optical characteristic as in a day time, andthe driver feels a glare light and can not see forward of theautomobile. Therefore instead of the two positions prism mirror typeanti-glare rearview mirror for varying the reflecting angle, theautomatic anti-glare rearview mirror is used for detecting theilluminance of the backward light and the ambient light to vary thereflectivity automatically in order to provide in the rearview mirrorthe low reflectivity in the an anti-glare mode or the high reflectivityin the normal mode in case of necessity.

Recently, it has been proposed to use various anti-glare rearviewmirrors with the electronic structure of controlling the reflectionlight level having a certain mirror attaching angle. In those electroniccontrolled anti-glare rearview mirrors, there have been mirror which usethe liquid crystal layer or an electrochromic device (ECD). For example,U.S. Pat. No. 4,902,108 discloses an advanced control for EC mirrorusing ECD and a mechanical anti-glare rearview mirror or the liquidcrystal type anti-glare rearview mirror.

In the EC mirror, a sealed chamber is formed by a transparent frontglass, an edge seal and a reflecting layer and is filled with asubstance having a determined EC characteristic (EC layer). Atransparent conductive layer (electrode) is provided on both top andrear surface of EC layer and a determined control signal (voltage) isapplied thereon from an electronic circuit.

The response speed of ECD is relatively slow compared to the human eyescharacteristic, and is available for the automatic anti-glare rearviewmirror. In respect to a drive circuit and a backward light and ambientlight comparative circuit, detailed descriptions are respectivelydisclosed by U.S. Pat. No. 4,902,108 and Japanese Patent Application No.Hei 6-99291, and an example of the normal construction thereof is shownin FIG. 14. In FIG. 14, a value detected by an ambient light levelsensor 10 and a backward light level sensor 11 is compared by a backwardand ambient light level comparison circuit 12 to supply an output, saidoutput and an output of an enforced DAY circuit 13 are applied to a gatecircuit 14, and EC mirror 20 is actuated via an anti-glare rearviewmirror drive circuit 15 by the output of the gate circuit 14. The drivecircuit 15 branches the output of the gate circuit 14 to connectinverters INV 1 and INV 2 in parallel with each other and further toconnect inverters INV 2 and INV 3 in series, transistors Q1, Q2 areconnected in parallel with forward and backward of the inverter INV 1respectively, while transistors Q3, Q4 are connected in parallel withforward and backward of the inverter INV 3 respectively, and EC mirror20 is provide with positive and negative voltages in accordance with theoutput, of the gate circuit 14.

As described above, in principle the automatic anti-glare rearviewmirror operates in an anti-glare mode by reflecting a glare light of thebackward automobile during night time. Normally the ambient light level(illuminance) and the backward light level (illuminance) are comparedwith each other, and said anti-glare mode is performed. The backwardlight level sensor and the ambient light level sensor are used fordetecting the light level with a CdS(Cadmium Sulfide) device normallyused. FIG. 15 shows a characteristic diagram of a relation of anilluminance and a resistance value of a popular CdS device. In eachembodiment of the present invention which will be described hereinafter,CdS device is used for respective sensors as described above.

A diagram 7 of FIG. 16 indicates a characteristic of an anti-glare mode(mirror sensitive characteristic) of the popular automatic rearviewmirror to show a relation of the ambient light illuminance (light level)and the backward light illuminance (light level). Normally, a range ofthe anti-glare mode is set in upper side (oblique line) of a line B ofthe diagram 7 and the rearview mirror operates in the anti-glare mode inprinciple by a combination of the ambient light illuminance and thebackward light illuminance within the oblique line range. The ECrearview mirror can have an intermediate reflectivity, the anti-glaredegree (varying mode of the rearview mirror reflectivity) becomescontinual depending on the drive circuit.

When the backward sight is bright in the day time, for example theautomobile is running the mountain bottom facing toward the mountainside and the mirror reflects the backward very bright sun shine, it isnot necessary for the mirror to operate in the anti-glare mode, howeverdepending only on the function described hereinbefore, there is a fearthat the rearview mirror operates in the anti-glare mode.

To overcome above described useless anti-glare mode of the mirror inuse, it is popular to form the automatic anti-glare rearview mirror sothat it is enforced in normal mode (hereinafter referred to as "EnforcedDAY function") when the ambient light illuminance (brightness) is over acertain level (normally several tens lux). As shown by the diagram 7 ofFIG. 16, an enforced DAY function is provided and the mirror isprevented from operating in the anti-glare mode to reflect the ambientilluminance (brightness) over a certain level (a right side of line D).The anti-glare mode is shown within the oblique line crossing part ofthe diagram 7.

This enforced DAY function is also adapted in EC mirror. For example,Japanese Patent Application No. Hei 6-99291 filed by the applicant ofthe present invention, discloses an electronic circuit for controlling areflectivity variable characteristic of ECD to perform the anti-glareoperation and includes the enforced DAY function not only to control thereflectivity variable level of EC mirror but also to control theanti-glare mode of the mirror depending on the ambient light level so asto inhibit the useless anti-glare mode. The same circuit diagram asdescribed in the Japanese Patent Application No. Hei 6-99291 is shown byFIG. 17. As shown by a mirror sensitivity characteristic in a diagram 8of FIG. 18, a circuit constant is adjusted to saturate the diagram curveat a line D, and the same effect caused by the enforced DAY function isachieved. In the present invention, the example shown by FIG. 18 is alsoregarded as the enforced DAY function.

While an art technic to inhibit the reflectivity variable operationcompletely is known and is confused with the enforced DAY function, forexample, in U.S. Pat. No. 4,902,108 as described hereinbefore, it isdisclosed that the mirror is enforced to a normal mode in case of abackgear state (the automatic anti-glare control is prohibitedenforcedly). However these technics take a different view from theenforced DAY function for controlling the anti-glare mode by reflectingthe ambient light level.

There is still a disadvantage in the automatic anti-glare rearviewmirror system having the enforced DAY function. For example, when it isa day time and the backward is not so glare, the rearview mirror ishappened to be in the anti-glare mode and is colored at a place of thecomparative gray ambient light such as a tree shade. Further, otherdisadvantage is caused in the automatic anti-glare rearview mirror bythe enforced DAY function exactly, for example, in a night time and thebackward is actually glare in the comparative bright ambient place suchas a shopping arcade, however there is happened that the mirror is notcolored. It is difficult to detect the coloring or the breaching of themirror by an information from the light only since any light levels tobe compared easily become the same level of several ten lux extent.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an automaticanti-glare rearview mirror system which overcomes disadvantages such asstarting a useless anti-glare operation or performing no anti-glareactuation in necessity, and to achieve the high accurate anti-glaremode.

According to one of preferred embodiments of the present invention, anautomatic anti-glare rearview mirror system comprises an EC anti-glarerearview mirror with reflectivity which is variable by an ECD, a ECdrive circuit for operating the anti-glare mode of the anti-glarerearview mirror, drive power sources, an automobile backward light levelsensing device, an automobile ambient light level sensing device, abackward and ambient light level comparison circuit for automaticallyoperating the EC drive circuit under a certain mode based on an outputof the backward and ambient light level sensing device, an enforced DAYgeneration circuit for controlling the anti-glare mode of the backwardand ambient light level comparison circuit according to an ambient lightlevel, and an enforced DAY level control means for changing an operationstarting level of the enforced DAY generation circuit (13).

An automatic anti-glare rearview mirror further comprises an ECanti-glare rearview mirror with reflectivity which is variable by anECD, a driving power source, an automobile backward light level sensingdevice; an automobile ambient light level sensing device, an enforcedDAY generation circuit for operating an anti-glare mode of the rearviewmirror according to the ambient light level, an enforced DAY levelcontrol means for changing an operation starting level of the enforcedDAY generation circuit to a determined value, an oscillation device forrepeating an oscillation signal of H level and L level alternately andcapable of controlling duration times of H level and L level signalseparately, a reverse cycle control circuit for varying and controllinga duration time of one of levels of the oscillation signal generatedfrom the oscillation device according to the light level sensed by theambient light level sensing device and for varying and controlling aduration time of the other of levels of the oscillation signal accordingto the light level sensed by the backward light level sensing device,and an ECD drive circuit for reversing a polarity of a driving voltagesupplied from the driving power source and applying the voltage to theECD according to the H or L level of the oscillation signal generatedfrom the oscillation device.

The ECD in drive circuit is set to drive the ECD a coloring direction atone of oscillation signal levels and to drive it in a bleachingdirection at the other level so that the reverse cycle control circuitoperates to short hold or long hold the duration time of one of levelsaccording to the greater ambient light level than the backward lightlevel or according to the lesser ambient light level than the backwardlight level respectively said reverse cycle control circuit operates toshort hold or long hold the duration time of the other level accordingto the greater backward light level than the ambient light level oraccording to the lesser backward light level than the ambient lightlevel respectively, and said ECD in drive circuit is set to drive saidECD a beaching direction at one of oscillation signal levels and todrive it in a coloring direction at the other level so that the reversecycle control circuit operates to long hold or short hold the durationtime of one of levels according to the greater ambient light level thanthe backward light level or according to the lesser ambient light levelthan the backward light level respectively. Said reverse cycle controlcircuit operates to long hold or short hold the duration time of theother level according to the greater backward light level than theambient light level or according to the lesser backward light level thanthe ambient light level respectively.

In the embodiment of the present invention, an anti-glare rearviewmirror system is provided, wherein said reverse cycle control circuitincludes first and second reverse cycle control circuits. Said firstreverse cycle control circuit is provided with a first photoconductivecell with resistance value which is reduced according to the automobileambient light level received therein, first resistor and first Diodeconnected in series with said first photoconductive cell and secondresistor connected in parallel with said first photoconductive cell.Said second reverse cycle control circuit is provided with a secondphotoconductive cell with resistance value which is reduced according tothe automobile ambient light level received therein, third resistorconnected in series with said second photoconductive cell, second Diodein the reverse direction of said first Diode and forth resistorconnected in parallel with said second photoconductive cell. Saidoscillation device includes such a composition that said first andsecond reverse cycle control circuits are connected in parallel witheach other on a feedback trace and-a duration time of one of oscillationsignal levels is shortened when resistance value of said firstphotoconductive cell becomes low, while a duration time of the otheroscillation level is shortened when resistance value of said secondphotoconductive cell becomes low.

Said enforced DAY level control means is a clock circuit to change anoperation starting level of said enforced DAY generation circuit to adetermined value by an output on a certain date and/or during a certaintime. Said enforced DAY level control means automatically varies anoperation starting level of said enforced DAY generation circuit to adetermined value by an output from an external equipment such as a lightswitch ON. Said enforced DAY level setting means includes a compositionthat an operation starting level of said enforced DAY generation circuitis set at any time by switches operated by the driver. Or said enforcedDAY level setting means includes a composition that an operationstarting level of said enforced DAY circuit can be continuously adjustedat any time by variable controllers operated by the driver.

According to the embodiment of the present invention, the enforced DAYlevel control means varies the operation starting level of said enforcedDAY circuit on a date and/or during a time determined by the output ofthe clock circuit. For example, during the night time depending on aseason in a year, when the automobile is running through the ambientbright shopping arcade, the operation starting level of the enforced DAYfunction is made up by the backward automobile light so that thedriver's eyes are protected from a glare light. While at the ambientdark place such as under the tree shade and the backward is brightduring the day time, said level is made down to control the anti-glaremode of the mirror, and it is comfortable for the driver that the mirroris prevented from operating in the anti-glare mode.

Corresponding to the light switch ON the automobile of the enforced DAYlevel control means level up the operation level of the enforced DAYcircuit. Therefore during the night time and when the automobile isrunning through the ambient bright shopping arcade, the driver's eyesare protected from the glare light by an adequate anti-glare mode causedby the backward automobile light. Further in the present invention, thedriver can operate the enforced DAY level setting means, for exampleswitches or variable controllers, to adjust the mode level of theenforced DAY circuit at any time by his decision to prevent the uselessaction (too sensitive anti-glare mode or stop action in case ofnecessity) which are described hereinbefore and the mirror mode can beset to the preferable characteristic individually. Further the mode canbe set again depending on the change of the running environment easily.

The above and further objects, details and advantages of the presentinvention will become apparent from the following detailed descriptionof preferred embodiments thereof, when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of operation of an anti-glare rearview mirror systemaccording to the preferred embodiment of the present invention;

FIG. 2 is a diagram of an another modified embodiment according to thepresent invention;

FIG. 3 is an electronic circuit diagram of the embodiment of theanti-glare rearview mirror according to the present invention;

FIG. 4 is an electronic circuit diagram of the other modified embodimentof FIG. 3 according to the present invention;

FIG. 5A is a diagram indicating an actuation characteristic of anenforced DAY function of FIG. 3;

FIG. 5B is a diagram illustrating an actuation characteristic of anenforced DAY function of FIG. 4;

FIG. 6 is an electronic circuit diagram of a further embodimentaccording to the present invention;

FIG. 7 is a diagram illustrating an actuation characteristic of theenforced DAY function of the embodiment of FIG. 6;

FIG. 8 a circuit diagram of a reverse cycle control circuit according tothe present invention;

FIG. 9 is a diagram illustrating an actuation characteristic of theenforced DAY function of the system which the circuit of FIG. 8 is used;

FIG. 10 is a partial circuit diagram of the other embodiment accordingto the present invention;

FIG. 11 is a diagram illustrating an actuation characteristic of theenforced DAY function of the system which the circuit of FIG. 10 isused;

FIG. 12 is a partial circuit diagram illustrating a further modifiedembodiment according to the present invention;

FIG. 13 is a diagram illustrating an actuation characteristic of theenforced DAY function of the system which the circuit of FIG. 12 isused;

FIG. 14 is an electronic circuit diagram illustrating embodiments of adrive circuit and a backward and an ambient light level comparisoncircuit of an conventional anti-glare rearview mirror;

FIG. 15 is a diagram illustrating an illuminance-resistance valuecharacteristic of a typical Cds device used for the conventionalautomatic anti-glare rearview mirror;

FIG. 16 is a diagram illustrating a sensitive characteristic (anti-glaremode characteristic) of the rearview mirror by a relation of the ambientlight illuminance (level) and the backward light illuminance (level) ofthe system of FIG. 15;

FIG. 17 is an electronic circuit diagram illustrating an otherembodiment according to the conventional automatic anti-glare rearviewmirror; and

FIG. 18 is a diagram illustrating a sensitive characteristic of therearview mirror which the circuit of FIG. 17 is used.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One of preferable embodiments of the present invention will be describedin connection with the accompanying drawings.

In the conventional anti-glare rearview mirror, the actuation of theenforced DAY function has been dependent on the information from theseveral ten lux ambient light level only and there has beendisadvantages as described hereinbefore. In the present invention, theinformation other than the light level can be supplemented to reflectthe rearview mirror according to the actual condition, in which anactuation level (threshold level) of the enforced DAY function iscontrolled to change by an enforced DAY level control means or anenforced DAY level setting means as described hereinbelow or theenforced DAY function of itself can be inhibited under an adequatecondition as described hereinbelow to prevent the mirror from uselessanti-glare mode or an out of order condition. FIG. 1 and FIG. 2illustrate block diagrams of the embodiment of the present invention andFIG. 10 and FIG. 12A illustrate circuit diagrams of the system of thepresent invention.

In FIG. 1, the backward and the ambient light illuminance (bright levelinformation)is obtained by a backward light level sensing device (11)(sensor) and an ambient light level sensing device (sensor)(10) and iscompared and calculated by a backward and an ambient light levelcomparison circuit (12), and the result therefrom is inputted to one ofan input terminal of AND circuit (14). In an enforced DAY generationcircuit (13), the ambient brightness (voltage value) is compared andcalculated with a level (standard voltage) according to a certainbrightness of an actuation base and the result thereof is inputted toanother input terminal of AND circuit (14). In an anti-glare rearviewmirror drive circuit (15), a voltage and an electric current aresupplied by a signal from AND circuit (14) to make the rearview mirrorin an anti-glare mode or a normal mode. For example, "H" level isoutputted for a direction of making the mirror an anti-glare mode, while"L" level is outputted for a direction of a normal mode.

An enforced DAY level control means (or an enforced DAY level settingmeans) indicated by a numeral (16) is connected to the enforced DAYgeneration circuit (13) to input an information other than the lightlevel in order to change the ambient light level (actuation point) so asto operate the enforced DAY. For example "H" level is outputted when themirror is enforced to be in an anti-glare mode and "L" level isoutputted for a normal mode. As described hereinafter, for informationsother than the light level, there are a clock circuit, a switchco-operating with an outer system, a switch or a volume for reflecting adriver's intention or the like.

A power source voltage from a battery (18) is constant and Supplied toIC or the like in circuits of each parts of the system by a stabilizedconstant voltage supply circuit (17).

FIG. 2 illustrates a schematic diagram of an embodiment of the system ofthe present invention applied to a semi-circuit disclosed by JapanesePatent Application No. Hei 6-99291 in FIG. 17. The enforced DAY levelcontrol means (enforced DAY level setting means) (15) is connected tothe output of the ambient light level sensing device (10) to reflect(calculate and inhibit as a gate or the like, for example) theinformation other than the light level (the output from the clockcircuit, the switch and the volume or the like) so as to change theambient light level (actuation point) to operate the enforced DAY. Theambient light level of the enforced DAY can be changed by the structuredescribed above, and the sustaining time ratio(duty ratio) of "H" or "L"level output from the reverse cycle control circuit (24) is changed.Further the backward light level sensing device (12), an oscillationdevice (23), EC device drive circuit (22), EC device (20A: anti-glarerearview mirror) and the driving power source (21) are constructedentirely the same as in FIG. 17.

Further detailed embodiment of the present invention will be describedin connection with the accompanying drawings. FIG. 3 illustrates a blockdiagram of an embodiment of the anti-glare rearview mirror of the firstinvention, in which the central part thereof is approximately equal toFIG, 14, and the system is composed of the backward light level sensingdevice (11) (sensor), the ambient light level sensing device (10)(sensor), the backward and ambient light level comparative circuit (12),AND circuit (14), the enforced DAY generation circuit (13), theanti-glare rearview mirror drive circuit(15) and EC anti-glare rearviewmirror (20).

In the embodiment, the output of a clock circuit (26) is connected tothe enforced DAY generation circuit (13) to perform an enforced DAYlevel control means (16A). A partial potential resistance divides thesupply voltage an intermediary point of said resistance is connected toa standard input terminal of the comparator for setting the ambientlight level (an actuation point) to operate the enforced DAY function,and one of resistance values of said partial potential resistance is setto vary depending on an output of indicating a determined term of theclock circuit (for example, a certain time zone or a certain term of theyear). In the embodiment, the potential resistance value is changed by aresistance of a fixed resistance and a transistor which is connected inparallel therewith to be conducted by a timer output. A power sourcecircuit is also indicated in FIG. 3 for a reference.

As described hereinbefore, the system of the embodiment contains a clockcircuit (26) to change the ambient light level of the enforced DAY inaccordance with a time. A timer function of the clock circuit isutilized to set the enforced DAY operation level which changes every dayand night time, a timer is set ON at PM 6:00 and set OFF at AM 6:00. Forexample, the ambient light level of the enforced DAY during a gray timePM 6:00 to AM 6:00 is set on a line of D-2 of a diagram of FIG. 5A,while the level during a bright time AM 6:00 to PM 6:00 is set on a lineof D-1. The rearview mirror system is set as described above to becomethe anti-glare mode at the comparative bright place such as the shoppingarcade and the backward being glare in the night time during AM 6:00 toPM 6:00, and to overcome the disadvantage of becoming the anti-glaremode at the comparative dark place such as the tree shade in a day timeand the backward being bright during AM 6:00 to PM 6:00.

In a system which the clock circuit (26) having a calender function, itis possible to set it in consideration of a season, for example, a timeris set ON at PM 7:00 and is set OFF at AM 5:00 in a summer season. In awinter season, the timer is set ON at PM 5:00 and is set OFF at AM 7:00so that the starting level of the enforced DAY function is up to adjustwith the actual night time, and it is more preferable to adjust thesystem operation with an actual using condition.

FIG. 4 illustrates a block diagram of another embodiment according tothe circuit diagram of FIG. 17 and the clock circuit (26) is simplified.The enforced DAY level control means (16B) also composed of the clockcircuit (26) is connected in said circuit to change the enforced DAYoperation level, in which the output of the clock circuit (26) drives arelay (RL1) so that said relay contact (RL1') is connected to a feedbackresistance of a pulse generator (16a) of a coloring side and thefeedback resistance value (that is a duration time of the pulse) ischanged due to an excitation of the relay (RL1) so as to equivalentlychange the enforced DAY function starting point. FIG. 4 illustrates anembodiment of an EC anti-glare rearview mirror drive device as shown byFIG. 2, in which "L" level is set to be one of oscillation signalsgenerated by the oscillation device 23, "H" level is set to be theanother, and one level for driving the mirror in the coloring directionand the other level for driving it in the bleaching direction areillustrated. In the driving power source 21, +12 V direct current isinput from the battery to be converted to approx. +1.6 V direct voltageby the positive power circuit 27 and to be converted to approx. -1.6 Vdirect voltage by the negative power source circuit 28. These positiveand negative power source circuits 27, 28 are efficiently composed of aswitching power source without providing special spaces for containingit in the mirror housing and further with less heating.

In FIG. 4, a reverse cycle control circuit 24 is provided in a feedbackloop of the oscillation device 23 and the ambient light level sensingdevice and the backward light level sensing device are provided in thereverse cycle control circuit 24. In the oscillation device 23, theresistance R5, two inverters 30, 32 are connected with each other inseries and inverters 30, 32 and capacitor C1 are connected with eachother in parallel. Capacitor C1 is charged in a time constant and theoutput of inverters 30, 32 is reversed when the voltage thereof is overthe threshold level of the inverter 30, and the oscillation is performedby repeating said actuation. The oscillation cycle t is obtained byformula t=2.2 R0 . C1 and the duty ratio t1:t2 of the oscillation signalbecomes approx. 1:1 in case that inverters 30, 32 are composed of CMOSIC.

In FIG. 4, the reverse cycle control circuit 24 of the oscillationdevice 23 is composed of a coloring side pulse generator 24a and ableaching side pulse generator 24b. The coloring side pulse generator24a is composed of CdS to comprise the ambient light level sensingdevice and the resistance and diode D1 connected to the relay contactRL1' in series. The bleaching side pulse generator 24b is composed ofCds to comprise the backward light level sensing device, diode D2connected to said DdS in series and the resistance R4 connected to saidCdS in parallel. The change of the enforced DAY level of the embodiedsystem is shown by a diagram 2 of FIG. 5B. It is also possible toovercome the disadvantage at the gray time described above by changingthe ambient light level of the enforced DAY to D-2 at the night time andby changing it to D-1 at the day time.

In the embodiments illustrated in FIG. 3 and FIG. 4, the system iscomposed of an anti-glare rearview mirror for an automobile which iscapable of an extinction of a reflection light, a rearview mirror drivecircuit for making the mirror to be anti-glare mode, a backward lightand an ambient light level comparison circuit to automatically operatesaid rearview mirror under a certain mode in accordance with an outputof both a backward light level measuring sensor and a ambient lightlevel measuring sensor, and an enforced DAY circuit to operate ananti-glare mode of said backward and ambient light level comparisoncircuit according to the ambient light level, especially furthercomposed of a clock circuit and an enforced DAY level control means tochange an operation starting level of said enforced DAY circuit to adetermined value on a date and/or during the time determined by anoutput of said clock circuit.

In the embodiment of described above, the output of the clock circuit isreflected on the enforced DAY level setting to fit the operation of theautomatic anti-glare rearview mirror with an actual environment, whilethere is an available case of changing the enforced DAY level by anoutput from an external equipment. It is preferable for an actualcondition that said enforced DAY circuit operation level can be changedaccording to a light switch ON of the automobile. Therefore theswitching ON/OFF of the light may be set an information from theexternal equipment so that the light ON switch is provided as theenforced DAY level control means (16) to set the ambient light level ofthe enforced DAY on a line of D-2 as illustrated by a diagram 1 (diagram2) of FIG. 5A and FIG. 5B at the time of the light being ON (the nighttime ), while to set it on a line D-1 at the time of the light beingOFF. Further instead of the clock circuit output in the embodimentillustrated by FIG. 3 and FIG. 4, it is simply possible to compose thecircuit for inputting a signal from a terminal which conducts anelectricity at the time of the light switch ON, and those are not shownin the drawing to overcome the overlapping.

The system is composed as described above, and normally the driverswitches the light ON during a night time at the comparative brightplace as a shopping arcade or the like so that the enforced DAY level isset to be up and the rearview mirror operates in becomes the anti-glaremode adequately to protect the driver from a backward glare light.

It may be possible to set the information of the external equipment tocorrespond with ON/OFF of a back gear. When the automobile is runningback and the backward is bright more or less, it is easy for the driverto confirm the backward by the normal mode of the rearview mirror withthe ambient light level down. Further in respect to the operation of themirror in case of the above, the starting level of the enforced DAYfunction is changed while an automatically anti-glare mode system iskept. It is different from the conventional art that the operationprovides cooperating with the back gear to prohibit the anti-glareaction of the rearview mirror as described hereinbefore.

The embodiment of the present invention which is described above isbased on a technical idea to automatically change the enforced DAY levelaccording to the information from the external equipment. While anadequate level of the enforced DAY function can not be determined due toan individual difference and for an actual practice, it often happensthat the mirror is not operated properly by a fixed enforced DAY levelsetting. Further the adequate enforced DAY level becomes different inaccordance with a running environment.

Therefore the free action of the anti-glare rearview mirror may beachieved by setting the ambient light level (setting value) foroperating the enforced DAY function to change depending on the driver'sdecision any time of necessity, and the system of said embodiment isillustrated by a block diagram of FIG. 6.

In the embodiment, the driver can change the ambient light level of theenforced DAY any time of necessity by a switch (SW1). The main partsrelating to the anti-glare operation of the circuit of FIG. 6 are sameas the one illustrated by FIG. 3. The partial potential resistance 3 tosupply the standard voltage to the comparator of an enforced DAYgeneration circuit (13) is composed of three contacts switch (SW10)capable of switching each resistance (R14, R15, R16) so that the partialpotential ratio is switched in three stages and changed to the accordingenforced DAY level. The driver operates the switch (SW10) which isdisposed around the driver's seat to change a sensitivity characteristicof the enforced DAY. In the embodied system illustrated by FIG. 6 inwhich R11 to R16 are respectively set values as shown in FIG. 6, theenforced DAY level can be set in three stages as illustrated by acharacteristic diagram 3 of FIG. 7.

In the embodiment described above, the automatic anti-glare rearviewmirror can be used more comfortably by changing the setting thereof ifnecessary so that the ambient light level of the enforced DAY is set atthe D-1 position, the rearview mirror is prevented from becoming theanti-glare mode in the day time at the comparative ambient dark placessuch as the tree shade or the like even if the backward is bright. Whenit is set at the D-3 position, the mirror operates in the anti-glaremode in the night time at the comparative ambient bright places such asthe shopping arcade and the backward glare.

Similarly, it is possible to compose a circuit provided with the switchaccording to the circuit illustrated by FIG. 4. It is not shown indetail, however the coloring side pulse generator of FIG. 4 can bereplaced by an electrical network (16c: coloring side pulse generator)which includes a switch (SW20) illustrated by FIG. 8. Respectiveresistance (R21 to R24) values are set as illustrated in FIG. 7, and thesetting as shown by a diagram 4 of FIG. 9. Of course the switch (SW20)is disposed around the driver's seat to switch the sensitivitycharacteristic of the enforced DAY and the driver can operate it ifnecessary.

In the embodiment described above, the enforced DAY level is changed tomultiple stages by a switch and the driver can adjust the enforced DAYlevel continuously by a use of a variable resistor as illustrated by ablock diagram of FIG. 10. A partial resistor is composed of a volume(VR3) and a resistance (R34) connecting in series with each other toperform as an enforced DAY level setting means (16D). An operationbottom of the volume (VR3) is disposed at the driver's seat at least.Respective volume and resistance (VR 3, R31 to R34) values are set asillustrated in FIG. 8A and a setting illustrated by a diagram 5 of FIG.11 is obtained to set the enforced DAY level at an optional levelbetween DV1 to DV2. It is preferable to use a rotation type or a slidetype variable resistor (VR3). Further it is more preferable to use aresistor clicking at the variable position and the driver can set thelevel of the enforced DAY without checking the operation bottom.

As described above, the driver can change the ambient light level of theenforced DAY to multiple stages in accordance with his decision by usingthe volume.

Further it is possible to provide the volume in the embodimentillustrated by FIG. 4 so that the coloring side pulse generation part isreplaced with the electrical network (16C: coloring side pulsegenerator) including a volume (VR4) as illustrated by FIG. 12 (wholesystem is not shown). The operation bottom of the volume (VR4) isdisposed at the driver's seat. Respective resistance (VR4, R41, R42)value are set as illustrated in FIG. 12 and the setting is obtained asillustrated by a diagram 6 of FIG. 13. The enforced DAY level can be setto an optional level between DV1 to DV2 to enable the driver tocontinuously change the ambient light level of the enforced DAY tomultiple stages if necessary.

In the third embodiment of the present invention as described above, thesystem is composed of a rearview mirror for an automobile capable ofadjusting the extinction of a reflected light, a circuit for driving therearview mirror in an anti-glare mode, a backward light and an ambientlight comparison circuit for automatically operating the rearview mirrorunder the certain mode based on, outputs of both backward light leveldetecting sensor and ambient light level detecting sensor, and anenforced DAY circuit for controlling the anti-glare node of saidbackward light and ambient light level comparison circuit in accordancewith the ambient light level. Further it is characterized in that anenforced DAY level setting means is provided in the system to change theoperation level of said-enforced DAY circuit. Moreover, it is moreuseful to compose said enforced DAY level setting means so that theoperation starting level of said enforced DAY circuit can be changed anytime or continuously by a switch to be operated by the driver any timeor by a variable controller to be operated by the driver.

In the embodiment described above, an electrochromic rearview mirror isprincipally used in the system and it may be possible to use other prismtype of the crystal type anti-glare mirror and adequate drive circuitswill be respectively adapted. Resultantly the system may be an automaticanti-glare rearview mirror having an enforced DAY function, and theadequate anti-glare mode is achieved to be more useful by adapting eachembodiment of the present inventions. Further each embodiment of thepresent invention may be applied double in the system that the enforcedDAY level can be operated by the clock circuit and simultaneously thevolume can be provided at the driver's seat enabling to set the enforcedDAY level by the driver so as to function with each other.

In the system of the present invention, the enforced DAY level controlmeans is provided to change the operation starting level of saidenforced DAY circuit on a date and/or during the time to be determinedby the clock circuit and the output of said clock circuit, or theenforced DAY level setting means is provided to change the operationlevel of said enforced DAY circuit according with the light switch ON ofthe car of itself, and the hight quality automatic anti-glare rearviewmirror can be achieved and a needless operation of the system for a lowambient light level is improved, that has not been achieved by theconventional system.

In the system, the enforced DAY level setting means is provided tooperate and change the operation level of said enforced DAY circuit atany time, especially said enforced DAY level setting means is providedas the switch. Said enforced DAY level setting means is formed to be thevariable controller which can be operated by the automobile driver sothat during the automobile running, the driver can control the operationof the automatic anti-glare rearview mirror to increase the dangerpreventing effect by adjusting the adequate enforced DAY level at anytime and the enforced DAY level may be set individually to use thesystem more comfortably.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in anautomatic anti-glare rearview mirror system, it is not intended to belimited to the details shown, since various modifications and structuralchanges may be made without departing in any way from the spirit of thepresent invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by letters patent isset forth in the appended claims.

We claim:
 1. An automatic anti-glare rearview mirror system, comprisingan anti-glare rearview mirror with a variable reflectivity; areflectivity varying device for varying the reflectivity of saidanti-glare rearview mirror; a driving power source; an automobilebackward light level sensing device; an automobile ambient light levelsensing device; an enforced generation circuit for operating ananti-glare mode of said rearview mirror according to an ambient lightlevel sensed by said automobile ambient light level sensing device; anenforced level control means for changing an operation starting level ofsaid enforced generation circuit to a determined value; an oscillationdevice for repeating an oscillation signal of a first level in whichsaid rearview mirror is in an anti-glare mode and a second level inwhich said rearview mirror is in a normal mode alternately and forcontrolling duration times of said signal of said first level and saidsecond level separately; a reverse cycle control circuit for varying andcontrolling a duration of time of one of the levels of the oscillationsignal generated by said oscillation device according to a light levelsensed by said ambient light level sensing device and for varying andcontrolling a duration time of the other of the levels of saidoscillation signal according to a light level sensed by said backwardlight level sensing device; and a drive circuit for reversing a polarityof a driving voltage supplied from said driving power source andapplying the voltage to said reflectivity varying device according tosaid first level or said second level of said oscillation signalgenerated by said oscillation device, said drive circuit being formed todrive said reflectivity varying device in a coloring direction at one ofthe oscillation signal levels, and to drive said reflectivity varyingdevice in a bleaching direction at the other signal level so that saidreverse cycle control circuit operates to hold short or hold long aduration of time of one of the levels according to a greater ambientlight level than the backward light level or according to a lesserambient light level than the backward light level respectively, whilesaid reverse circuit control circuit operates to hold short or hold longa duration time of the other level according to a greater backward lightlevel than the ambient light level or according to a lesser backwardlight level than the ambient light level respectively, said drivecircuit being formed to drive said reflectivity varying device in ableaching direction at one of the oscillation signal levels and to drivesaid reflectivity varying device in a coloring direction at the othersignal level so that said reverse cycle control circuit operates to holdlong or to hold short a duration of time of one of the levels accordingto a greater ambient light level than the backward light level oraccording to a lesser ambient light level than the backward light levelrespectively, while said reverse cycle control circuit operates to holdlong or to hold short a duration time of the other signal levelaccording to a greater backward light level than the ambient light levelor according to a lesser backward light level than the ambient lightlevel, respectively.
 2. An automatic anti-glare rearview mirror systemas defined in claim 1, wherein said enforced level control means is aclock circuit for changing the operation starting level of said enforcedgeneration circuit to a determined value by an output on a certain date.3. An automatic anti-glare rearview mirror system as defined in claim 1,wherein said enforced level control means is a clock circuit forchanging the operation starting level of said enforced generationcircuit to a determined value during a certain time.
 4. An automaticanti-glare rearview mirror system as defined in claim 1, wherein saidenforced level control means is formed so as to automatically vary theoperation starting level of said enforced generation circuit to adetermined value by an output from an external equipment.
 5. Anautomatic anti-glare rearview mirror system as defined in claim 4,wherein said enforced level control means automatically vary theoperation starting level of said enforced generation circuit by theoutput from the external equipment formed as a light switch ON.
 6. Anautomatic anti-glare rearview mirror system as defined in claim 1,wherein said enforced level setting means includes switches operated bya driver formed so that the operation starting level of said enforcedgeneration circuit is settable at any time by said switches operated bya driver.
 7. An automatic anti-glare rearview mirror system as definedin claim 1, wherein said enforced level setting means includes variablecontrollers operated by a driver formed so that an operation startinglevel of said enforced generation circuit is continuously adjustable atany time by said variable controllers operated by a driver.
 8. Anautomatic anti-glare rearview mirror system as defined in claim 1,wherein said enforced level control means includes at least two elementswhich are external equipment.
 9. An automatic anti-glare rearview mirrorsystem as defined in claim 8, wherein said two elements include a clockcircuit and a light switch ON.
 10. An automatic anti-glare rearviewmirror system as defined in claim 1, wherein said two elements include aswitch and a variable controller operated by a driver.
 11. An automaticanti-glare rearview mirror system as defined in claim 1, wherein saidreverse cycle control circuit includes first and second reverse cyclecontrol circuits, said first reverse cycle control circuit beingprovided with a first photo-conductive cell with a resistance valuereduced according to an ambient light level received from saidautomobile ambient light level sensing device, a first resistor and afirst diode connected in series with said photo-conductive cell and asecond resistor connected in parallel with said first photo-conductivecell, said second reverse cycle control circuit being provided with asecond photo-conductive cell with a resistance value reduced accordingto an ambient light level determined by said automobile ambient lightlevel sensing means, a third resistor connected in series with saidsecond photo-conductive cell, a second diode in a reverse direction ofsaid first diode, and a fourth resistor connected in parallel with saidsecond photo-conductive cell, said oscillation device being formed sothat said first and second reverse cycle control circuits beingconnected in parallel with each other on a feedback trace and a durationtime of one of the oscillation signal levels is shorted when aresistance value of said first photo-conductive cell becomes low, whilea duration time of the other oscillation signal level is shortened whenthe resistance value of said second photo-conductive cell becomes low.